Furnace



W. J. LAWRENCE FURNAGE Filed Feb. 19, 1920 2 Sheets-Sheet l May 'I 1923.;

W. J. LAWRENCE FURNACE lliltlturitetll lllllay it, lilium,

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.ltpplicaten filed February i9, 1920. Ster-iai No. 360,008.

ino all 'wlw/m it may concer/a `Be it known that l, FFILLTIAM lJl. li/iwnmvcn, a citizen ofthe United States, residing at Toledo, in the county of Lucas and tl @tate of Ohio, have invented new and useful llmprovements in Furnaces, of which the following is a specification.

i My invention relatesI to furnaces and particularly to automatic means for regulating it the supply of air to the` burning fuel. in boiler furnaces and the like which are given fresh charges of coal at frequent intervals. When a fresh charge of bituminous coal is "spread over an incandescentJ fuel bed, the it? coal is heated rapidly and to ll0% of the combustible matter is distilled off in the form of gases and tar vapors. This process is usually nearly completed in two to live minutes after firing. The distilled combus au tible matter requires for its combustion a large amount of additional air. 'llo burn the volatile combustible material, about fifteen times its weight of air must be supi plied thereto, so that immediately after at firing, a large quantity of air should be admitted over the lire and this quantity should be gradually reduced as the distillation of the volatile combustible nears completion. After distillation is completed only a comparatively small quantity of air need be ad initted over the fuel bed.

'llhe primary object of my invention is to provide automatic means for supplyingthe air in the required amount immediately after each fresh charge of fuel has been introduced to the furnace and to gradually. reduce this amount so that the proper supply of air is furnished at all times. This resuits in complete combustion, high efficiency4 and economy of fuel, and elimination of smoke.

ln carrying out my invention ll provide suitable means operated bythe feed door of the furnace to control the supply of air. The arrangement is such that the closing of the feed. door after each fresh charge of coal is introduced, automatically opens the dampe'rs which regulate the supply of air to the furnace, so that air is admitted in suffiA cient volume to effect complete combustion. rlihe dampers are then automatically grad ually moved toward a closed position to effeet a correspondin,er reduction `of the air supply, the movement being controlled by a dash pot or other retarding element, so that after the volatile combustibles have been burned the supply of air is restricted to the comparatively small amount then needed. Loss of heat due to an excess of air is thus prevented.

@ther features of the invention will appear hereinafter.

ln the accompanying drawings:

Figure l is a sectional elevation of a furnace constructed in accordance with my in vention, portions of the furnace being omitted.

Figure 2 is a sectional plan of that portion of the furnace on one side of the longitudinal center line. i

Figures 3 and l. are sectional elevations at the plane of the line lfb-B, showing respectively the draft dampers in closed and open positions.

Figures 5, 6 and 7 are front elevation views of the furnace, showing the damper lcontrolling devices in different positions. Figure 5 shows the feed door closed and the dampers down in their normal or draftchecking position. Figure 6 shows the furnace door open for introducing a fresh charge, the dampers still being down while the feed door remains open. Figure 7 shows the position of parts immediately after the furnace door has closed, the dampers being now open.

Figure 8 is a detail view on a larger scale of the damper controlling` mechanism.

Figure 9 is a fragmentary view of such mechanism looking in a direction at right angles to that of Figure 8.

The furnace comprises a combustion chamber' l() in the front wall of which is an opening ll for1 the introduction of fuel, said opening being` normally closed by the feed. door l2. The air for combustion enters ports 13 beneath the grate bars 14: and passes upward through passagcways l5 in the side walls of the furnace, being thereby preheated, and enters the combustion chamber through the ports 16 above the grate. 'F he gases of combustion `are conveyed rearwardly in the general path indicatedby the arrows, passing beneath a baffle wall 17 and thence rearwardly beneath theboiler 18.

The baffle wall 17 serves to secure an even distribution of the air over the lire bed by preventing the air from forming currents Ill() or flowing in restricted paths or channels over the fire bed. By admitting the air through the ash pit or below the grate and passing it upward through the side walls of the furnace, it is heated to a high temperature before entering the combustion chamber, thus increasing the efficiency.

The amount of air admitted to the combustion chamber is controlled by dampers 20 and 2l arranged over the openings 13 and which normally restrict the amount of air admitted to said openings. These dampers are automatically swung upward to a wide open position by the closing of the feed door ll after a fresh charge of fuel has been introduced'. The dampers are then permitted to gradually swing down, for the purpose already pointed out. rlhe mechanism for operating and controlling the dampers will now be described.

A link 22 is pivotally connected at one end to the feed door l2 and at its opposite end is connected by a pivot 23 to a bar 24 slidable lengthwise in guide brackets 25 and 26. Above the slide bar 24 is a rock shaft 27 to which is Xed a lever 28. One end of said lever is connected through a vertical link 29 to an arm 30 connected to the damper 20` The rod 29 may also be connected through a link 3l with an arm on the damper 2l. The other end of the lever 28 is connected through a link 32 and piston rod 33 to the piston 34 of a dash pot 35. Said piston may be provided with a valve 36 opening upward to permit the piston to move downward freely, a restricted opening 37 being provided to allow a slow upward movement of the piston, which may work in oil. A crank arm 40 is adjustably secured to the shaft 27 by a set screw 41 (Fig. 9). Pivoted to said crank arm is a dog 42. The downward movement of the dog about its pivot is limited by a shoulder 43 which engages with the arm 40. An adjustable lug 44 is mounted on the slide bar 24 in position to engage in front of the dog 42 when the feed door is opened.

Normally the parts are in the position shown in Figure 5. When the attendant opens the feed door to introduce a fresh supp y of fuel, the slide bar 24 is moved to the left to the position indicated in Figures 6 and 8, permitting the dog` 42 to drop behind the lug 44. When the attendant closes the feed door, the bar 24 is thereby pulled to the right and through the dog 42 and arm 40, rocks the shaft 27 in a counter clockwise direction, thereby rocking the lever 28 to the Figure 7 position. This moves the piston downward in the dash pot and at the same time through the connections 29, 3() Vand 3l swings the dampers 2O and 2l upward to the wide open position. As the feed door is being closed, the dog 42 is carried upward by thev upward movement of the arm 40 sufficientlyto disengage the lug 44 and permit it to move to the right of the dog, so that the latter is free to swing from the Figure 7 position back to the l `igure 5 position independently of said slide bar. the 7 feed door remaining closed.

After the feed door is closed the weight of the dampers and connected parts slowly returns the mechanism to the Figure 5 position. lt will thus be seen that while the feed door is open the dampers remain down, but they are automatically opened wide by the closure of the feed door, permitting a large volume of air for the combustion chamber, which is required to produce complete combustion of the volatile elements which are rapidly given oil from the fresh fuel. rllhisvsupliily of air is then gradually reduced at a rate corresponding to the reduction of the volatile elements, so that when the latter are burned out, the supply of air is limited to the comparatively small amount needed to vsustain the continued combustion.

Although the dampers on both sides of the furnace are shown as operated from a single door, it will be understood that when double doors are used the dampers on opposite sides may be conveniently operated separately by the two doors. The dash pot 35 is shown merely as au example of a retarding device, as various other standard or approved retarding devices n'xight serve the same purpose. It will also be understood that various modifications of the damper controlling mechanism might be employed and that these and other changes or modifications may be resorted to within the spirit and scope of my invention.

What I claim is:

l. In a furnace, the combination of a combustion chamber, a grate therefor, the side walls of said chamber being formed with air passages extending from beneath the grate and opening into the combustion chamber above the grate, dampers contro]- lingl said passages, a fuel door, means operated by the closing of said door to open said dampers, and automatic. means to effect a gradual movement of the dampers toward closed position.

2.111 a furnace, the combination of a combustion chamber, a grate therefor. the side walls of said chamber being formed with air passages extending from beneath the grate and opening into the comlnistion chamber above the grate, dampers controlling said passage, mechanical connections between the dampers and the feed door of the furnace for opening the dampers by thc closing of the door, and automatic means to then cause a slow movement of the dampcrs toward closed position.

A furnace comprising in combination a combustion chamber, a grate, the side walls llU et the furnace being :provided with air channels leading from the ash pit beneath the grate upward through the furnace walls and opening into the combustion chamber above the grate, dempers beneath the grate eont'ollng Seid. channels, means operated by the closing of the feed dootl to open seid dempe's, and automatic means to @euse :L slow closing of said dempers after the feed door is Closed.

` Signed at Toledo, in the County of Luces and c@tate of Uho, this 12th day of Februery, 1920.

WILLIAM J. LAWRENCE. 

